1. Field of Invention
The present invention relates to a TENS (Transcutaneous Electric Nerve Stimulator) electrode that utilizes carbon fiber as the conductive body, hence outshines its peer products with its high conductivity and exceptional softness.
2. Related Art
The Transcutaneous Electrical Nerve Stimulator (TENS), one of the most important contrivances used by the physiotherapists in the world, puts out prescribed electrical currents to stimulate the nerves or muscle tissues and treats many physical problems. The TENS electrodes are essential to a TENS, because only through these electrodes can the prescribed electrical currents be directed into the body.
FIG. 3 shows the structure of a conventional TENS electrode. A layer of self-adhesive conductive gel (60), the conductive body (61) mounted on the self-adhesive conductive gel (60), an isolating tape (62) mounted on the conductive body (61). A lead wire (70) with the first terminal electrically provided between the conductive body (61) and the isolating tape (62). The self-adhesive conductive gel (60) is made of electrically conductive material to direct electrical current into the body. The self-adhesive conductive gel (60) is to be positioned at the treatment site on the skin. The second terminal (71) of the lead wire (70) connects the TENS. Conventionally, the material to fabricate the conductive body (61) is chosen from aluminum foil, stainless steel fiber cloth or the carbon film.
When the conductive body (61) is made of aluminum foil, high conductivity will be expected. However, the aluminum foil is too hard to go with the protrude body parts such as the knees or the elbows, and does not always fit in with the contour of the human body. Further, the bond force between the conductive body (61) and the self-adhesive conductive gel (60) is weak because of the low adhesion force of metal, i.e. the aluminum foil. So when such electrodes are removed from the body, the conductive body (61) and the self-adhesive conductive gel (60) are often separated. Another downside of the aluminum foil electrodes is electrolysis, a factor that will not only cause pain at the treatment site but also reduces shelf life of the product.
Another choice for the conductive body (61) is stainless steel/polyester fiber. The softness of the mixed fabric is better than that of the aluminum foil but is vulnerable to the electromagnetic interference from nearby electrical appliance. Further, the impedance of such conductive medium can be as high as 30 ohms PSI.
When the conductive body (61) is made of another nonmetal material, carbon film, the advantage is that electromagnetic interference caused by nearby electrical appliance can be avoided. Conventionally, the carbon powder and the plastic film are the fundamental materials to produce the carbon film, wherein the carbon powder is sprayed on the plastic film. However, the carbon film hardness is difficult to snugly attach on protruded body parts such as the knees or the elbows because of the high hardness. The impedance of the carbon film is determined by the quantity of the carbon powder sprayed on the plastic film. Usually, the impedance of such carbon film can be as high as more than several tens ohms PSI. If the quantity of the carbon power is increased to improve the conductivity, the carbon film may be broken during the producing process.